Programmable and reconfigurable humidity-driven actuators made with MXene (Ti₃C₂T_x)-cellulose nanofiber composites for biomimetic applications

Smart actuators have a wide range of applications in bionics and energy conversion. The ability to reconfigure shape is essential for soft actuators to achieve various shapes and deformations, which is a crucial feature for next-generation actuators. Nonetheless, it is still an enormous challenge to establish a straightforward approach to creating programmable and reconfigurable actuators. MXene-cellulose nanofiber composite film (MCCF) with a brick-and-mortar hierarchical structure was produced through a vacuum filtration process. MCCF demonstrates impressive mechanical properties such as a tensile stress of 68 MPa and a Young’s modulus of 4.65 GPa. Besides, the MCCF highlights its potential for water-assisted shaping/welding due to the abundance of hydrogen bonds between MXene and cellulose nanofibers. MCCF also showcases capabilities as a humidity-driven actuator with a rapid response rate of 550°·s⁻¹. Using the methods of water-assisted shaping/welding, several bionic actuators (such as flower, butterfly, and muscle) based on MCCF were designed, highlighting their versatility in applications of smart actuators. The research showcases the impressive capabilities of MXene-based actuators and offers beneficial insights for the advancement of future intelligent materials.